Metal Additive Manufacturing (MAM) is a transformative technology with the potential to revolutionize manufacturing through the production of complex, high-value components with unprecedented design freedom. However, the adoption of MAM is challenging due to its complex and multifaceted nature, which encompasses a wide range of advanced technologies, including Laser Powder Bed Fusion (LPBF), Direct Energy Deposition (DED), and Binder Jetting (BJ).  To address this challenge, this research delves into a Systematic Literature Review (SLR) of n=71 publications and expands upon a prominent existing MAM readiness model as theoretically proposed by the research literature.  This enriched model offers a nuanced understanding of MAM readiness, catering to the intricacies of this rapidly evolving field.  Notably, it provides a more fine-grained assessment of competency levels, enabling better strategic planning and resource allocation.  The research also highlights the implications of these findings for Small and Medium-sized Enterprises (SMEs) operating in the realm of MAM, suggesting avenues for SMEs to enhance their competitiveness.  The expanded MAM readiness model seeks to serve as a comprehensive and up-to-date tool for assessing an organization's readiness to adopt MAM technology.  It is particularly valuable for SMEs, which may lack the resources and expertise to independently assess their MAM readiness.  Furthermore, this research may be used to support SMEs in navigating their material, data, and personnel interface with Large System Integrators (LSIs).